Reconstruction of a human skull calibration phantom using bone sections from an 241Am exposure case

New York University Medical Center's Institute of Environmental Medicine (NYUMC/IEM) was called upon by representatives of the United States Transuranic Registry to reconstruct a human skull phantom for the purpose of producing a calibration structure to be used for determining 241Am skeletal content from in vivo measurements. The human skull represented a deposition pattern of 241Am in the bone matrix which had accumulated into the bone via natural metabolic processes after an accidental intake. Soon after death, the skull was sagittally divided and the left lateral side was analyzed radiochemically. Assuming symmetry of deposition, and based on measurements of the right lateral side of the skull performed at NYUMC/IEM as well as results of radiochemical analysis of sections of the left side, the activity content of the right side was estimated to be 307 +/- 4 Bq (8.3 +/- 0.1 nCi). The right side was subsequently paired with a blank left lateral of a control skull and embedded into tissue-equivalent material. The reconstructed skull phantom was then evaluated to determine its applicability as a calibration phantom which could be used to estimate skeletal burdens of 241Am.